The Spectrum of Double Hit Lymphomas

Double-hit lymphomas (DHLs) characterize a unique subset of B-cell non-Hodgkin lymphomas. DHL typically presents in older adults with high-risk clinical features. This entity carries a significantly inferior prognosis compared with typical cases of diffuse large B-cell lymphoma; however, emerging literature can identify discrete clinical features within DHL that are associated with a favorable prognosis. Emerging literature is also demonstrating that intensive upfront treatment strategies may improve outcome. Diagnosis, prognostication, and management of DHL are reviewed, as well as potential future directions incorporating novel biologically targeted therapies. Finally, double-expressing lymphomas (DELs) will be discussed and contrasted with DHL.